/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | foam-extend: Open Source CFD
   \\    /   O peration     | Version:     4.1
    \\  /    A nd           | Web:         http://www.foam-extend.org
     \\/     M anipulation  | For copyright notice see file Copyright
-------------------------------------------------------------------------------
License
	This file is part of foam-extend.

	foam-extend is free software: you can redistribute it and/or modify it
	under the terms of the GNU General Public License as published by the
	Free Software Foundation, either version 3 of the License, or (at your
	option) any later version.

	foam-extend is distributed in the hope that it will be useful, but
	WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
	General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with foam-extend.  If not, see <http://www.gnu.org/licenses/>.

\*---------------------------------------------------------------------------*/

#include "interpolateXY.H"
#include "primitiveFields.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

template<class Type>
tmp<Field<Type> > interpolateXY
(
	const scalarField& xNew,
	const scalarField& xOld,
	const Field<Type>& yOld
)
{
	tmp<Field<Type> > tyNew(new Field<Type>(xNew.size()));
	Field<Type>& yNew = tyNew();

	forAll(xNew, i)
	{
		yNew[i] = interpolateXY(xNew[i], xOld, yOld);
	}

	return tyNew;
}


template<class Type>
Type interpolateXY
(
	const scalar x,
	const scalarField& xOld,
	const Field<Type>& yOld
)
{
	label n = xOld.size();

	label lo = 0;
	for (lo=0; lo<n && xOld[lo]>x; ++lo)
	{}

	label low = lo;
	if (low < n)
	{
		for (label i=low; i<n; ++i)
		{
			if (xOld[i] > xOld[lo] && xOld[i] <= x)
			{
				lo = i;
			}
		}
	}

	label hi = 0;
	for (hi=0; hi<n && xOld[hi]<x; ++hi)
	{}

	label high = hi;
	if (high < n)
	{
		for (label i=high; i<n; ++i)
		{
			if (xOld[i] < xOld[hi] && xOld[i] >= x)
			{
				hi = i;
			}
		}
	}


	if (lo<n && hi<n && lo != hi)
	{
		return yOld[lo]
			+ ((x - xOld[lo])/(xOld[hi] - xOld[lo]))*(yOld[hi] - yOld[lo]);
	}
	else if (lo == hi)
	{
		return yOld[lo];
	}
	else if (lo == n)
	{
		return yOld[hi];
	}
	else
	{
		return yOld[lo];
	}
}


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// ************************************************************************* //
